MCX - Blue jump
Classical blue jump list, probably the strongest deck of the meta right now, it can win every matchups even if it's countered by red decks.
I find this deck realy hard to pilot, you have a lot of choices available each turn, it's really important to think in term of faeria advantage (sometimes, a trade that you find great with prophet of tides + aurora isn't that great because your creature will get flame bursted or wind soldiered...)
Try to collect on your opponent's wells as early as possible to reduce your colosses and put a maximal pressure on his orb wth 4 faeria 7/7, 3 faeria 4/5 jump and buffed ninja toads or triton warriors.
Against red, try to not overextend to reduce the value of their aoe.
Your land placement is decisive hen playing blue, take a spot next to your opponent's well to play mystic beasts, try to build as few lands as possible to draw a lot and have a maximum of possibilities.
Mulligan: keep some early jumpers collectors like battle frog, triton trainer, triton warrior... Depending on your hand, you can consider keeping prophet of tides and even mystic beast in some situations, to have a quick start.